As far as I can tell world boss respawn times are blizzlike. I think with the ability for a single person to kill a world boss the CD should be reduced to 1 day or less to increase the chances of finding one.
The loot from these bosses is not game-breaking and I would like to try killing them without spending 20 minutes running across the map only to find out that it isn't there and not having any idea when it will respawn.